package com.itany.corejava.day02;

public class Test3 {

    public static void main(String[] args) {
        int a=1;
        a+=2;//a=a+2

        System.out.println("a = " + a);

        System.out.println("1==2 = " + (1==2));

        System.out.println("1==1 = " + (1==1));


        String s1=new String("abc");
        String s2=new String("abc");
//        String s1=null;
//        String s2=null;

        System.out.println("s1 = " + s1);
        System.out.println("s2 = " + s2);

        System.out.println("s1==s2 = " + (s1 == s2));

        System.out.println("s1.equals(s2) = " + s1.equals(s2));


        System.out.println("5%2 = " + 5 % 2);//1
        System.out.println("5%-2 = " + 5 % -2);//1
        System.out.println("-5%2 = " + -5 % 2);//-1
        System.out.println("-5%-2 = " + -5 % -2);//-1


        int i=2;
        System.out.println(i<<2);

        i=8;
        System.out.println(i>>1);

        i=-1;
        System.out.println(i>>54);
        System.out.println(i>>>31);

        int aa=6;
        int bb=12;
        System.out.println("aa&bb = " + (aa & bb));
        System.out.println("aa|bb = " + (aa | bb));
        System.out.println("aa^bb = " + (aa ^ bb));



        int ii=0;
        System.out.println("~ii = " + ~ii);

        String username=null;

        if(null==username || username.equals("")){
            System.out.println("用户名不能为空");
        }
        

    }
}
